This application is related to devices and techniques for measuring optical polarization of light.
Optical polarization is an important parameter of an optical signal in various optical systems. For example, in fiber optic communication systems, polarization-dependent effects in fibers and other devices, such as polarization-dependent loss (PDL) and polarization-mode dispersion (PMD), can have significant impacts on performance and proper operations of optical devices or systems. Hence, it may be desirable to measure and monitor the state of polarization (SOP) and the degree of polarization (DOP) of an optical signal in these and other systems.
Optical polarimeters are devices designed to measure polarization of light and can be implemented in various configurations. Some commercial polarimeters use rotating waveplates to control the polarization of the input light and measure optical power levels of the controlled input light for determine the Stokes parameters of the input light. Such polarimeters can be bulky, expensive, slow, and have a relatively short life time, and therefore may not suitable for certain applications such as system applications in fiber networks. Some other polarimeters use four optical detectors and require complicated beam-splitting optics. Therefore, these polarimeters can also be bulky, expensive and difficult to align and calibrate.